One of the conventional causes for vehicle-related accidents such as an accident between vehicles, an accident between a vehicle and a passer-by, etc. is considered an oversight or a misjudgment by a driver on a passer-by, other vehicle, an obstruction or the like in the surroundings of the vehicle, for example due to low visibility by the weather (rain, snow, etc.) or temporary decreased vision of the driver by eyestrain and others. That is, the driver is unable to have a correct understanding of the state of the surroundings of the vehicle. Thus, there is a delay in risk aversion, which leads to an accident. To put it the other way around, if the driver can have a correct understanding of the state of the surroundings of the vehicle, an accident can be avoided.
A conventionally known image display device can project an outside state or landscape on a window glass of a vehicle (see Patent Document 1, for example).
The image display device described in this Patent Document 1 includes an observation device that observes a state of the vehicle (position, velocity, and others), and an accumulation device that preaccumulates image information of outside landscapes. Based on information indicating a position of the vehicle observed by the observation device, image information of a landscape which can be possibly seen outside the vehicle at an observed position is obtained from the accumulation device. An image represented by the image information is displayed on a window glass. Map information such as a name of a place, a name of a river, a name of a mountain, etc. can be also displayed. The displayed image can be also sequentially switched according to velocity based on velocity information of the vehicle. As such, one of the image display devices can display on a window glass of a vehicle a landscape image of the surroundings of the vehicle.    Patent Document 1: Unexamined Japanese Patent Publication No. 2004-20223